Polymer compositions are utilized in a variety of applications, including so-called "industrial rubber applications". Industrial rubber applications include hoses, belts, electrical cable insulation, automotive and industrial weatherstripping, profiles, molded parts and the like. Many articles for industrial rubber applications are produced through extrusion techniques, i.e. the polymer composition is extruded through a die then cooled or chemically hardened.
Fillers are often utilized in polymer compositions to impart desirable characteristics such as reinforcement, pigmentation and/or conductivity to the polymer compositions. Carbon blacks have been widely utilized as fillers and reinforcing pigments in the compounding and preparation of polymer compositions. Carbon blacks are generally characterized on the basis of one or more of their properties including, but not limited to, their surface areas, surface chemistry, aggregate sizes, and particle sizes. The properties of carbon blacks are analytically determined by tests known to the art, including iodine number (I.sub.2 No.) and dibutyl phthalate adsorption (DBP).
The dispersion properties (dispersibility) of a filler are relevant to the use of fillers in polymer compositions. It is generally advantageous to have fillers which are easily dispersible in polymer compositions.
Many types of polymer compositions are cured using an UHF microwave curing process. UHF microwave curing is becoming increasingly important due to its high curing efficiency and other desirable attributes. As understood in the art, UHF microwave curing refers to a curing process utilizing ultra high frequency microwaves (from about 300 to 3000 megahertz (megacycles per second or "MHz")). Polymer compositions that are more receptive to UHF microwave curing have a faster heating rate and thus are advantageous for processing the material.
Generally, polymer compositions incorporating high surface area carbon blacks are more receptive to UHF microwave curing. However, high surface area carbon blacks are often difficult to disperse in polymer compositions. It would be advantageous to have a carbon black composition which is easily dispersible in polymer compositions and/or which imparts increased UHF receptivity to the polymer composition.